A four-day strike by Johannesburg municipality workers ended today when a union leader was arrested and more than 1,000 black strikers were fired.

About 1,200 who refused to return to work here were loaded into buses and taken under police escort to the black homelands of Transkei and Venda or to the sprawling black township of Soweto.

The strike, which at one time had the support of about 10,000 of the 12,000-member black work force, affected municipal services and left heaps of garbage rotting in the streets. The workers were demanding more pay and the right to union representation.

Joseph Mavi, the leader of the black Municipal Workers' Union that called the strike, was arrested early today at the Supreme Court, where he was seeking an injunction to prevent City Council and police action against union members.

The union is not recognized by the white-run city government.

The strike was the latest outburst of unrest that has been sweeping South Africa in recent months and it marked a new challenge to the Pretoria government.

The walkout by municipal workers in this industrial city followed a series of strikes, mostly in the automobile industry, in the Cape Province in the past several weeks.

Despite the city government's announcement today that the strike had been broken, a number of white volunteers, mainly schoolboys, were still seen picking up uncollected garbage left over from the strike.

According to police, Mavi was being held for investigation under the sabotage and riotous assemblies acts. However, lawyers for Mavi's union were told that he was being detained under a section of the General Law Amendment Act providing for 14 days detention without trial. The period can be renewed by a judge's order.

Council officials took a hard line with the strikers yesterday, threatening immediate dismissal for those who refused to return to work. Workers were interviewed individually and asked if they wished to return.

The moderate newspaper Rand Daily Mail reported that City Council officials and police armed with shotguns rifles, and semiautomatic pistols went to black housing areas during the night and rounded up those ordered dismissed. They were then loaded into fleet of buses and driven to their designated tribal homelands.

City Management Committee Chairman Johan Oberholzer denied that there had been any coercion.

"They all returned to work willingly, and those who wanted to go home were paid off," he said.

The strikers wanted the minimum weekly pay raised from $43 to $75, in addition to recognition to their union. City officials argued that the workers had just received a pay raise on July 1 that boosted the weekly minimum wage from $39.50.

Mavi's union claims about 9,000 members among Johannesburg's black municipal workers. By the third day of the strike on Wednesday, however, at least 10,000 black workers were off the job.